refactoring: case(for square root)

src/main/c/Calculator/calculator.c

@@ -88,7 +88,12 @@ double combination(int n, int r);
             return log(num1);
         case 8:
             return pow(num1, num2);    
-
+        case 9:
+            return sqrt(num1);
+        case 10:
+            return num1 * num1;
+        case 11:
+            return num1 * num1 * num1;